DE102007039581A1 - Apparatus and method for monitoring access to a patient - Google Patents

Abstract

The invention relates to a device and a method for monitoring a patient access, in particular for monitoring the venous vascular access in an extracorporeal blood treatment, in which an arterial tubing, which has an arterial needle or cannula, blood taken from the patient and via a venous tubing, the a venous needle or cannula is supplied to the patient blood. The device according to the invention and the method according to the invention are based on the use of a special needle or cannula for patient access. The needle or cannula 8 is designed so that air is drawn in as a result of the liquid flowing through the needle or cannula when the needle or cannula is outside the vessel access, whereby sound is generated. An improper vascular access is detected with high certainty by the fact that the environment is monitored for the occurrence of sound, in particular the sound propagated via the venous tubing of the extracorporeal blood circulation. A preferred embodiment of the monitoring device according to the invention provides that the needle or cannula 8 is designed as a type Venturi nozzle with a narrowing 8 C of the cross section and an opening 8 D.

Description

The The invention relates to a device for monitoring access to a patient for a facility, using the needle or cannula to the patient a liquid is supplied, in particular for monitoring venous vascular access in an extracorporeal blood treatment, in excess an arterial tubing, which is an arterial needle or Cannula, blood taken from the patient and over a venous tubing that is a venous needle or cannula supplied to the patient blood becomes. Moreover, the invention relates to a blood treatment device with an extracorporeal blood circulation, over a Device for monitoring venous vascular access features. Furthermore, the invention relates to a method for monitoring a vascular access.

On In the field of medical technology facilities are known with which Liquids taken from a patient and the patient Liquids can be supplied. It can provide access to the patient with a needle or cannula for Puncturing of vessels. While the examination or treatment is a proper one To ensure access to the patient. Therefore, it is necessary to monitor patient access.

One Application with particularly high demands on safety vascular access provides extracorporeal blood treatment in which, via an arterial blood line, the one arterial puncture needle or cannula, the patient Blood is drawn, the blood is passed through a dialyzer and via a venous blood line, which is a venous Puncture needle or cannula, the patient again is supplied. It exists despite regular monitoring patient access by the hospital staff in principle the danger of having the venous needle or cannula slipped out of the blood vessel of the patient unnoticed. While slipping out of the arterial cannula associated with a suction of air into the arterial tubing is that leads to an alarm and interruption of treatment is Slipping out of the venous cannula and the so dreaded free flow of blood into the environment not without to detect more. When slipping out of the venous Cannula but not immediately recognized, the patient can bleed to death.

to Solution to this problem are different in the prior art Devices known. Some of these devices are standard Safety devices present in the blood treatment machines back and solve in case of an improper Vascular access an immediate interruption of the extracorporeal Circulatory system. The standard in the treatment machines existing safety devices are generally based on Monitoring the pressure in the extracorporeal blood circulation. In practice, however, has shown that alone with a monitoring the pressure in the extracorporeal blood circulation slipping out in particular the venous needle or cannula is not sufficient Security can be detected. Some known security devices Although they have sufficient sensitivity, they react but very sensitive to changes in the position of the patient, which often leads to false alarms. Another disadvantage is that the existing blood treatment devices are not readily available retrofit with the known monitoring devices but retrofitting a costly and expensive Intervention in the treatment machines requires.

From the US 2004/0254513 A1 there is known an extracorporeal blood treatment device having an extracorporeal blood circulation having an arterial and venous access monitoring device. The known monitoring device has two electrodes, one of which is arranged on the arterial and the other on the venous tubing to establish an electrical connection between the liquid in the respective tubing and a monitoring unit via two measuring lines. The monitoring unit measures the impedance between the two electrodes, indicating an improper vascular access if the impedance is not within preset limits. The disadvantage is that the monitoring of the vascular access requires additional electrodes and measuring leads.

The WO 97/10013 describes a monitoring device based on the monitoring of the pressure in the extracorporeal blood circulation, in which the pressure waves generated due to the heartbeat and propagating in the arterial and venous tubing lines are detected. The absence of pressure signals is considered an indicator of faulty vascular access.

The WO 2004/110528 A1 describes a device for checking an infusion pump, which is based on the monitoring of the sound emitted by the device during operation, which can be detected as a body or airborne sound. It is assumed that the infusion pump, when operated properly, generates sound that has certain characteristics. A faulty operating state is then concluded when the sound generated by the pump deviates from these characteristics. As a result, in particular drive errors, for example, on defective La ger, but also closures of the infusion catheter are recognized.

From the US-A-5,662,619 a venous needle is known for venous patient access in extracorporeal blood treatment. The venous needle has an oblique cut at the distal end. To reduce turbulence in the exit of the blood from the needle, it is proposed to provide lateral openings on the needle and to form projections projecting into the lumen downstream of the lateral openings and pointing counter to the direction of flow.

Of the Invention is based on the object to provide a device the secure monitoring of access to a patient, in particular the venous patient access in an extracorporeal Blood treatment allowed in a simple way.

A Another object of the invention is to provide an extracorporeal blood treatment device a monitoring device for venous patient access to provide a secure monitoring of access allowed in a simple way. An object of the invention is also to provide a method with which to easily access the patient can be monitored with high security.

The Solution of these objects is inventively with the features of claims 1, 9 and 11. Advantageous Embodiments of the invention are the subject of the dependent claims.

The Inventive device and the invention Procedures for monitoring patient access are based on using a special needle or cannula for the patient access. The needle or cannula is designed such as a result of flowing through the needle or cannula Liquid air is sucked in when the needle or Cannula outside the vascular access located. When aspirating air outside the vascular access In turn, sound is generated. Therefore, an improper Vascular access with high safety alone be recognized that the environment monitors for the occurrence of sound becomes.

It It has been shown that already sucking small amounts of air lead to a clearly audible noise can if the needle or cannula is not within the Vascular access is located. Therefore, it is possible slipping out of the needle or cannula from the vascular access to recognize with high security.

For the evaluation of the signal is basically not required that the sound is audible. The sound can also as pressure or density fluctuations in an elastic medium, d. H. Gases, liquids, solids can be detected, without the sound is audible. So can an evaluation of solid state vibrations, e.g. B. by means of a surface scan be done with a laser or by means of acceleration sensors, the for example, can be attached to the blood tube.

The Monitoring device according to the invention is characterized by the fact that it is easy to handle, inexpensive can be produced and retrofitted at any time. Especially finds the monitoring device according to the invention for monitoring venous vascular access in an extracorporeal blood treatment use. Another Field of application is the monitoring of patient access at an infusion device. In both cases is from a needle or cannula for patient access Made use of.

A preferred embodiment of the monitoring device according to the invention Foresees that the needle or cannula will narrow the cross-section and having an opening. The needle or cannula thus represents a kind Venturi nozzle. The cross-section reduction leads to an increase of the dynamic pressure and reducing the static pressure at the bottleneck. Thereby rises in the area of the constricted portion of the needle or cannula the speed of the needle or cannula flowing liquid, whereby a negative pressure arises. As a result of the negative pressure is through the opening in the needle or cannula aspirated air, generating sound, if the needle or cannula is not properly in place Patient's vessel is seated.

in principle are just a bottleneck in the needle or cannula as well only one opening is sufficient to produce sound can be proven safe. But it is also possible provide several bottlenecks or openings.

at In a particularly preferred embodiment, the constriction of the needle or cannula cross section through a constriction the needle or cannula created. But it is also possible that the bottleneck formed by inwardly projecting lugs becomes.

In a particularly preferred embodiment of the needle or cannula, the opening is a through-bore in the constriction of the needle or cannula or a through-cut in the wall of the needle or cannula. This ensures that air is sucked in the region of the greatest negative pressure. Basically, it is also possible Lich, the opening in the flow direction before or behind the bottleneck to arrange.

The Monitoring device according to the invention has an evaluation unit for recording of sound, which is designed such that when detecting sound on improper patient access is closed.

The Evaluation unit of the monitoring device according to the invention preferably has a sound transducer for the conversion of sound signals in electrical signals, which are in a simple manner with the known process and evaluate electronic circuits. When Sound transducers are all transducers with which sound signals can be converted into electrical signals. For example, electrodynamic, capacitive, piezoelectric or piezoresistive transducer.

The through the inflow into the needle or cannula Airborne noise is heard next to the audible, airborne sound, transmitted via the structure-borne sound, which is in the liquid and the subsequent Hose lines are propagated.

A another particularly preferred embodiment provides the structure-borne noise to detect an improper Monitor vascular access. At this Embodiment, the evaluation unit has over a structure-borne sound transducer for the conversion of structure-borne noise into electrical signals. As a structure-borne sound transducer can For example, piezo pickups or electret condenser microphones Find use.

Of the Structure-borne sound transducer is preferably on the hose line arranged, over which the structure-borne sound propagates. The permanent monitoring of the structure-borne sound signal allows a very short reaction time, since the interference signal coinciding with the disconnection of the needle or cannula occurs.

Instead of However, a structure-borne sound transducer can also be a Laser for surface scanning of the venous tubing or an accelerometer attached to the tubing be provided with which recognize pressure or density variations to let.

The electrical signals, which depend on the pressure or density variations of the sound transducer or the laser for Surface scan or the acceleration sensor are generated, basically in different ways be evaluated. In a preferred embodiment the amplitude of the electrical signal is monitored and compared with a predetermined reference signal. The evaluation unit then closes to an improper one Patient access when the electrical signal is greater than the reference signal is. This makes it possible to do that Distinguish output signal from interfering signals safely.

It but it is also possible, not just the amplitude of the signal but also the frequency of the signal in the evaluation to take into account. This is how typical sound sequences can be the signal to be evaluated, which also filtered out of the signal first can be. For example, a comparison with a Signal pattern possible, which for the sucking of Bubbles is characteristic. The signal processing can with the known analog or digital techniques.

The Monitoring device according to the invention preferably has means that in the detection of a not proper patient access an audible and / or visual alarm. In addition, at the detection of improper patient access a signal for intervention in the machine control the blood treatment device for interrupting the blood treatment be generated. For example, the blood pump can be stopped and by closing the venous tube clamp the venous blood line of the extracorporeal blood circulation the venous blood flow is interrupted.

in the Below is an embodiment of the invention below Referring to the drawings explained in more detail.

It demonstrate:

1 the essential components of an extracorporeal blood treatment device together with the device according to the invention for monitoring the patient access in a highly simplified schematic representation,

2 the venous needle or cannula of the extracorporeal blood circulation of the extracorporeal blood treatment device upon proper access to the patient's venous vessel;

3 the venous needle or cannula of 2 in an enlarged view,

4 the output signal of the sound transducer of the evaluation unit of the monitoring device according to the invention in a proper vascular access,

5 the venous needle or cannula, if the vascular access is improper,

6 the cannula of 5 in enlarged Presentation and

7 the output signal of the transducer of the evaluation unit in an improper vascular access.

1 shows the essential components of an extracorporeal blood treatment device, in particular a hemodialysis device, which has a device for monitoring the venous vascular access. The hemodialysis apparatus has a dialyzer 1 on, passing through a semipermeable membrane 2 in a blood chamber 3 and a dialysis fluid chamber 4 is divided.

To an artery of the patient is by means of an arterial puncture needle or cannula 5 an arterial tubing 6 connected to the inlet of the blood chamber 3 of the dialyzer leads. From the outlet of the blood chamber 3 of the dialyzer 1 goes a venous hose line 7 using a venous puncture needle or cannula 8th connected to a vein of the patient. The arterial tubing 6 is in an occlusive blood pump 9 inserted, which promotes the blood in the extracorporeal blood circulation I.

The dialysis fluid circuit II of the hemodialysis apparatus comprises a dialysis fluid source 10 at which a dialysis fluid supply line 11 connected to the inlet of the dialysis fluid chamber 4 of the dialyzer 1 leads. From the outlet of the dialysis fluid chamber 4 of the dialyzer 1 goes a dialysis fluid discharge line 12 from that to an outlet 13 leads. Into the dialysis fluid discharge line 12 is a dialysis fluid pump 14 switched to convey the dialysis fluid.

The control of the dialysis device assumes a central control unit 15 via control lines 16 . 17 the blood and dialysis fluid pump 9 . 14 controls.

Downstream of the blood chamber 3 of the dialyzer 1 is located on the venous tubing 7 an electro-magnetically actuated hose clamp 18 that have another control line 19 from the central control unit 15 is closed when the venous puncture needle or cannula should slip out of the vascular access. In addition, the control unit stops 15 after slipping out of the cannula the blood pump 9 ,

For monitoring the venous vascular access is a monitoring device 20 provided, which forms an independent unit or may be part of the dialysis machine. In the event that a conventional dialysis machine is to be retrofitted with a device for monitoring venous vascular access, the monitoring device is 20 an independent entity. Otherwise, the monitoring device is preferably part of the dialysis device, since the dialysis device already has various components that can be used by the monitoring device. These include, for example, the central control (microprocessor) of the dialysis machine and the power supply (power supply).

The monitoring device 20 has an evaluation unit 21 that have a data line 22 with a sound transducer 23 connected, the structure-borne noise at the venous hose line 7 measures. Instead of a structure-borne sound transducer, however, it is also possible to provide a laser for surface scanning of the venous tubing or an acceleration sensor attached to the venous tubing with which vibrations can be detected. The evaluation unit 21 communicates with the central control unit 15 the dialysis device via another data line 24 ,

The monitoring device 20 has an alarm unit 25 on that over a data line 26 with the evaluation unit 21 connected is. The alarm unit 25 , which may also be the central alarm unit of the dialysis machine, generates an audible and / or visual alarm when the monitoring device 20 detects an improper venous vascular access. In addition, the evaluation unit generates 21 in the event of improper vascular access, a control signal indicating the central control unit 15 the dialysis device via the control line 24 receive. If the central control unit 15 the control signal of the evaluation unit 21 receives, the blood treatment is interrupted, the control unit 15 the venous hose clamp 18 closes and the blood pump 9 stops.

The 2 and 3 show the venous puncture needle or cannula 8th for proper vascular access. At the needle or cannula is the tubing 7 connected to the structure-borne sound transducer 23 is appropriate.

at the needle or cannula is basically to a conventional puncture needle or cannula, the but is specially formed at the distal end.

To puncture the vessel 26 has the needle or cannula at the distal end an oblique cut 8A on. With proper vascular access, ie the needle or cannula is in the vessel 26 stung, flows through the lumen 8B the needle or cannula draws blood from the blood chamber 3 of the dialyzer 1 into the vessel 26 of the patient while blood of the patient at the same time through the blood vessel 26 flows. This blood flow is in the 2 and 3 marked with arrows.

At the distal end points the needle or cannula 8th a narrowing 8C which is formed by a constriction with a nozzle-shaped cross-section. The constriction 8C For example, describe the contour of a Venturi nozzle. In the area of constriction 8C the flow cross section is reduced in relation to the diameter of the needle or cannula by about 10 to 40%, preferably 15 to 25%. Within the constriction 8C There is a through hole in the wall of the needle or cannula 8D or a Durchgangsfräsung through the wall of the needle or cannula. Since the constriction increases the flow resistance, it should only be sized so large that the function is guaranteed.

at An embodiment is the needle outer diameter 1.8 mm, the smallest outer diameter of the constriction 1.5 mm, the length of the constriction is 2 mm and the diameter of the through hole is 0.3 mm. The relationship from the constriction to the diameter of the needle is 16%.

The Needle can be made, for example, in the example By cold forming a circumferential groove in the wall of a shaped thin-walled tube, so that the flow cross-section tapers. By selecting an appropriate shape for the stamping tool a suitable contour can be created.

The through hole 8D should be together with the constriction 8C as close as possible to the beginning of the cut 8A the needle or cannula, so that on the one hand it is ensured that with proper fit of the needle or cannula in the blood vessel of the patient whose lateral opening is always at a sufficient safety distance from the blood vessel, so that no air can be sucked, and on the other hand guaranteed in that, when the needle is pulled out, air can only be sucked in when the needle has already slipped out dangerously far, so that there is danger to the patient's life. In the embodiment, the bore is located 8D the tip of the needle or cannula opposite.

Due to the reduction of the flow cross-section arises in the region of the constriction 8C a negative pressure, leaving the vessel 26 Blood is sucked into the needle or cannula. This blood then flows back out of the needle or cannula back into the vessel. Because the hole 8D has a small diameter, the additional blood flow is relatively small or does not occur depending on the flow conditions, in particular due to the much larger compared to air viscosity of blood. This blood flow is in the 2 and 3 again indicated by arrows.

4 schematically shows the electrical output signal of the structure-borne sound transducer 23 , the evaluation unit 21 the monitoring device 20 receive. The electrical output signal has a DC component and an AC component. The alternating component of the output signal has only a very small amplitude attributable to interfering signals, since the needle or cannula sits correctly in the container ( 2 . 3 ).

The 5 and 6 show the case that the needle or cannula 8th from the venous vessel 26 has slipped out. Since the needle or cannula is no longer in the vessel, ambient air is sucked in due to the negative pressure. The sucked in ambient air is expelled again together with the inflowing blood. Sound is generated.

The noise generated by the incoming air is in addition to the audible airborne sound also as structure-borne noise in the blood and the adjoining the needle or cannula blood line 7 continued. The upstream of the needle or cannula 8th on the venous tubing 7 attached structure-borne sound transducers 23 measures the structure-borne noise that occurs in the improper vascular access.

7 schematically shows the electrical output signal of the structure-borne sound transducer 23 , It can clearly be seen that although the output signal has the same DC component as the output signal in the case of proper vascular access ( 4 ), but the alternating component of the structure-borne sound signal has a relatively large amplitude.

The evaluation unit 21 the monitoring device 20 has a comparison unit 21A for comparing the amplitude of the alternating component of the measured structure-borne sound signal with a reference signal. The reference signal is dimensioned such that it is significantly above the level of the interference signals, but also below the level that the alternating component of the structure-borne sound signal has in the event of improper vascular access.

For the detection of faulty vascular access can the evaluation unit via the specialist known facilities have, for example, a rectifier for rectifying of the output signal and a comparator for comparison with the reference signal or filter etc.

If the alternating component of the measured structure-borne sound signal is greater than the reference level, is closed to a faulty vascular access, ie concluded that the needle or cannula has slipped out of the vessel. The evaluation unit 21 then generates an alarm signal, so that the alarm unit 25 an audible and / or visual alarm and a control signal, so that the central control unit 15 the dialysis device, the venous hose clamp 18 closes, the blood pump 9 stops and stops the treatment. This prevents the dreaded free flow of blood.

At the Slipping out of the needle or cannula from the blood vessel occurs under certain flow conditions first a tiny stream of blood from the side hole, leaving air is sucked in only when the cut of the needle or cannula completely withdrawn from the blood vessel is because then eliminates the patient-side back pressure and the free flow into the environment occurs. So it's only then air sucked when the needle is completely pulled out of the blood vessel is.

In an alternative embodiment, the electrical signal of the structure-borne sound transducer 23 in the evaluation unit 21 the monitoring device 20 compared with a characteristic signal pattern that is characteristic of the sound that occurs after slipping out of the needle or cannula. When the characteristic signal pattern in the electrical signal of the structure-borne sound transducer 23 is detected, closes the evaluation unit 21 the presence of improper patient access.

at the method according to the invention is the sound signal only then generated and can only be detected when the needle or cannula already slipped out of the vessel is so that a blood treatment can no longer take place.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• US 2004/0254513 A1 [0005]
• WO 97/10013 [0006]
• WO 2004/110528 A1 [0007]
• - US 5662619 A [0008]

Claims (15)

A device for monitoring access to a patient for a device, with which a liquid is supplied to the patient via a needle or cannula, in particular for monitoring the venous vascular access in an extracorporeal blood treatment, in which via an arterial tube, which is an arterial needle or cannula Having taken blood from the patient and blood is supplied to the patient via a venous tubing, which has a venous needle or cannula, characterized in that the device ( 20 ) to monitor the patient access a needle or cannula ( 8th ), which is designed such that the needle or cannula draws air outside the vessel access as a result of the liquid flowing through the needle or cannula, so that sound is generated when the air is sucked in, and the device ( 2 ) for monitoring the patient access an evaluation unit ( 21 ) for detecting sound, which is designed such that upon detection of sound is concluded on an improper patient access. Device according to claim 1, characterized in that the needle or cannula ( 8th ) a narrowing ( 8C ) of the flow cross section with an opening ( 8D ) for generating a negative pressure due to the liquid flowing through the needle or cannula, so that in case of improper vascular access through the opening, air is sucked into the needle or cannula. Device according to claim 2, characterized in that the constriction of the needle or cannula ( 8th ) as a constriction ( 8C ), wherein the opening ( 8D ) is a through-hole or a through-cut through the wall of the needle or cannula. Device according to one of claims 1 to 3, characterized in that the evaluation unit ( 21 ) a sound transducer ( 23 ) for converting sound signals into electrical signals or a surface-scanning laser or an acceleration sensor that generates an electrical signal. Apparatus according to claim 4, characterized in that the sound transducer as a structure-borne sound transducer ( 23 ) is designed to convert structure-borne noise into electrical signals. Apparatus according to claim 5, characterized in that the structure-borne sound transducer ( 23 ) on the venous tubing ( 7 ) is arranged to detect sound propagating through the hose line. Device according to one of claims 4 to 6, characterized in that the evaluation unit ( 21 ) a comparison unit ( 21A ) for comparing the amplitude of the electrical signal with a predetermined reference signal, wherein the evaluation unit ( 21 ) concludes an improper patient access when the electrical signal is greater than the reference signal. Device according to one of claims 4 to 6, characterized in that the evaluation unit ( 21 ) a comparison unit ( 21A ) for comparing the electrical signal with a characteristic signal pattern, wherein the evaluation unit ( 21 ) concludes improper patient access when the characteristic signal pattern is detected in the electrical signal. Device according to one of claims 1 to 8, characterized in that the device for monitoring a vascular access means ( 21 . 25 ) which, upon detection of improper patient access, give an audible and / or visual alarm and / or generate a signal for intervention in the machine control of the blood treatment device to interrupt the blood treatment. Blood treatment device with an extracorporeal blood circulation comprising an arterial tubing ( 6 ) with an arterial needle or cannula ( 5 ) and a venous tubing ( 7 ) with a venous needle or cannula ( 8th ), and with a device ( 20 ) for monitoring the venous vascular access according to one of claims 1 to 9. Procedure for monitoring access to to a patient for delivery of a liquid the patient via a tubing with a needle or cannula, in particular for monitoring the Venous vascular access in an extracorporeal Blood treatment in which via an arterial tube, which has an arterial needle or cannula, the patient Taken from blood and via a venous tubing, which has a venous needle or cannula, the Patients are supplied with blood, characterized that for delivering the liquid to the patient a tubing is used with a needle or cannula which is designed so that the needle or cannula outside of the vascular access sucks air while the Fluid flows out of the needle or cannula, so that when sucking in the air, sound is generated and monitored whether sound is generated by the needle or cannula, being in the generation of sound on an improper Patient access is closed. Method according to claim 11, characterized in that a needle or cannula ( 8th ), which is a constriction ( 8C ) with an opening ( 8D ) for generating a negative pressure when a liquid flows through the needle or cannula, so that due to the negative pressure in an improper vascular access through the opening air is sucked into the needle or cannula. Method according to claim 12, characterized in that the constriction ( 8C ) of the needle or cannula ( 8th ) is formed as a constriction, wherein the opening ( 8D ) is a through-hole or a through-cut through the wall of the cannula or needle. Method according to one of claims 11 to 13, characterized in that the over the venous Tubing monitored for propagating structure-borne noise becomes. Method according to one of claims 11 to 14, characterized in that in the detection of an improper Patient access given an audible and / or visual alarm is and / or an intervention in the machine control of the blood treatment device to interrupt the blood treatment.